HTML is very easy to learn. It is a markup language and you can learn it in a couple of weeks.
Using only HTML, you can't build the website you see online. You will have to learn CSS also.

Start with HTML

If you do you have a faster internet connection, watch some YouTube videos. Understand how to markup elements the tags for different elements.

Then you can start adding designing and layouting the content using CSS language. It is also very easy to learn.

List of Some Popular Website to Learn HTML

* W3Schools.com
* html.net

Watch youtube videos and read articles on the above sites. I promise you can learn it very easily. These sites helped very much in learning web designing. Currently, I work for a web design company in Chennai. I learn about web designing more from online than I learned from the classrooms. You can also do that.